Because of advantages such as small volume, convenience of use, wearable devices are widely used for security controls in particular places such as shopping malls, venues, factories and so on. The wearable devices are worn by the people in the particular places and communicate with a server and a control center via base stations so that the control center can obtain information such as positions of the wearable devices timely.
The wearable device commonly uses a conventional input device, such as a microphone, a keyboard, etc. to transmit information to the control center. However, combining the conventional input device into the wearable device lead to a relative higher cost of the wearable device and also makes a volume and a power consumption of the wearable device increase.